<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Sugar</title>
  <style>
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    .header {
      /* 如果：100vw = 540px */
      width: 100vw;
      /* name：?vw = 74px */
      /* 适配公式： x / 540 * 100vw  */
      height: calc(74 / 540 * 100vw);
      background-color: #FF0000;
    }
  </style>
</head>

<body>
  <header class="header"></header>
  <script>
  </script>
</body>

</html>